1. Field
Example embodiments relate generally to methods of charging battery packs for cordless power tools.
2. Description of Related Art
Conventional charge algorithms for Li-ion battery packs typically employ a constant current/constant voltage (CC/CV) charge algorithm in which the charge current is held at a constant level for a period of time, while the battery pack increases in voltage to a set voltage threshold level, typically about 90% state of charge. At that point, the pack voltage is maintained at a constant voltage level while the current gradually decreases to a lower level so as to complete the charge.
For charging conventional Li-ion battery packs, the power supply (charger) supplying the charging current to the battery pack needs to maintain (at different times in the charge) a constant voltage and/or a constant current. This requires complicated or complex charge circuitry, especially when charging a battery pack with a number of serially connected cells with voltages of each cell potentially being at different levels. This constant current/constant voltage (CC/CV) charge algorithm is typically applied to conventional Li-ion battery packs which have cell chemistries such as lithiated cobalt oxide, lithiated nickel oxide, lithiated manganese oxide spinel, and mixtures of same or other lithiated metal oxides.